The subject method and system for retreading a track wheel is generally directed to reconditioning and/or reworking worn wheels for various vehicles operated on track rails. The subject method and system provide for their restoration, such that the wheels may be re-used rather than discarded. More specifically, the subject method and system are directed to the ‘retreading’ of such a worn track wheel sufficient to reconstitute its original profile.
Railway-type track wheels such as these are used on various types of vehicles, both powered and non-powered. Locomotives, railroad cars, cable cars, mining cars, wagons, coaches, and the like are but a few examples. In most track wheeled vehicles, power is applied by driving some or all of the track wheels, with traction relying on friction between the track wheel—typically formed of steel—and the railway tracks, which are typically also formed of steel or other metallic material.
During the course of repeated use, the wheels of these vehicles and track wheels wear out due to friction, slipping, and constant load against the railway track. Some track wheels tend to wear out more rapidly because they are typically formed of steel having a generally low Rockwell hardness as measured on a Rockwell hardness Scale.
Track wheels are typically formed of metallic material, such as steel. They are formed generally with a tread portion that slightly tapers inward from an outer flange portion. This keeps laterally opposed wheels engaged on the rail tracks they ride on. However, there tends to be slippage between the flange of a given wheel and the track rail it engages, leading to pronounced wear of the wheel's flange area. The tread of the wheel also tends to wear from the lateral swaying of the railway vehicle which tends to result, especially when the vehicle travels at higher speeds.
Other surfaces of the wheel may experience pronounced wear, depending on the particular use to which it is subjected. For instance, track wheels often encounter excessive wear at and around their exposed lateral side surfaces. The lateral side portions typically at both the flanged and opposing unflanged sides of the wheels tend to suffer premature wear due to repeated contact with switching, retarding, or other track mechanisms and hardware. In particular, those surfaces extending down from a tip of the flange down its side away from the tread repeatedly encounter frogs, switches, and retarders on typical railways that whose abrasive contact eats away at the wheel surfaces there over time.
Typically, once the track wheel is worn at its various surfaces, as determined by applicable safe operating standards—such as for safe minimum thickness of the flange—the wheel is disposed of. It is not unusual for railroad maintenance vehicles to wear through multiple sets of wheels during a typical year of operation. Invariably, this is at considerable replacement cost.
As shown in FIG. 1, a track wheel 100 includes a flange 110 at one side and a tread 120 having a tapered surface which extends from the flange to an opposing side 130. The flange 110 on the peripheral region of the track wheel 100 and the tapered tread 120 keep the track wheel from falling or sliding off the railway tracks. When a railway vehicle travels through a bend, the track wheel 100 does not pivot and displaces laterally off-center. The tapered profile of the tread acts as a self-centering correction mechanism to force the vehicle to travel true, but over time, the flange 110 and tread 120 surfaces wear out. Once worn, the track wheel 100 becomes unusable.
There are various systems known in the art relating to track wheels. For example, U.S. Pat. No. 1,519,029 is directed to a process for renovating worn flanged wheels. This reference first mentions the method of turning down a steel ‘tyre’ in which material is removed from the wheel to sculpt a new surface results in loss of valuable material. This method necessitated the need to match the wheel on the opposing side of the axle with the same amount of material removed.
The reference prescribes filling of material from the worn-down contour line B to the line E, then shaping the surface according to the prescribed contour line D. The approach is to keep quite close to the worn down tread so that the desired shape can be obtained with minimal cutaway of original material. The sectional surface to be obtained is limited on the one hand by B and E and on the other hand by D and comprises only a small fraction of that which would have had to be removed by the prior method. Accordingly, waste of the wheel's costly material turned to scrap is minimized. However, the fill material is limited to the flange area E. Part of the wheel material is necessarily turned down thereafter to obtain the prescribed contour line D.
U.S. Pat. No. 6,746,064 is directed to a composite wheel for tracked vehicles. The reference prescribes a wheel and flange of heat treated steel suitable for a particular end use. A portion of the inside surface of wheel flange, including the area of frictional contact between the wheel flange and rail, is machined away. A welded overlay of low friction material is applied to replace the material removed from an inside surface of flange.
Such known references, however, fail to provide a suitable system or method for resurfacing a worn track wheel to reconstitute its various portions, such as the tread and flange surfaces, to their original profile as disclosed herein.